Parameters of cation transport and permeability in the crystalline lens of the rabbit are being quantitated using electrophysiological and isotope flux experiments. Particular attention is given to the differences between anterior and posterior regions of the lens, and the relative role of epithelium and lens fibers in the control of cation and water balance. The possible role of cyclic AMP in the regulation of cation transport is also being investigated. Alterations of these parameters will be studied during the development of spontaneous cataract in an animal model. BIBLIOGRAPHIC REFERENCES: Paterson C.A., Neville M.C., Jenkins R.M. II and Cullen J.P.: An electrogenic component of the potential differences in rabbit lens. Biochem. Biophys. Acta 375:309-316, 1975.